1. Field of Invention
The present invention relates to a developing device, an image forming device, and a method of assembling the developing device. More specifically, the present invention relates to a structure in which a sealing member is mounted for preventing leaking of developer from both ends of a developing roller.
2. Description of the Related Art
A prior art image forming device of an electrophotography system is mounted to a printer, a multi function peripheral, a facsimile machine and so on. An electrostatic latent image formed on a photosensitive drum is developed by a developing device having developer (toner or the like) stored therein to form a toner image. A transfer device transfers the toner image onto a recording paper. A fusing device fuses the transferred toner image on the recording paper.
In the developing device in the image forming device as described above, a magnet roller as a developing roller is inserted into a developing sleeve. The developing sleeve is rotatably supported by a casing. The magnet roller is fixed to the casing. The developing sleeve is rotated relative to the magnet roller. For example, in the developing device having a two-component developer stored therein, the developer is adhered to the outer surface of the developing sleeve to form a magnetic brush. Toner particles are transferred from the magnetic brush to the outer surface of the photosensitive drum by static electricity, and an electrostatic latent image on the photosensitive drum is developed into the toner image.
In general, in the developing device, a sealing member is adhered to the inner wall of the casing and the developing sleeve slides in tight contact with the sealing member. Therefore, leaking of the developer from the interior of the casing to the side is prevented. More specifically, a blade is provided on the developing device, and the blade cuts bristles of a carrier nap. One end surface of the sealing member is pressed against the blade. Therefore, the outer side surface of the sealing member is brought into tight contact with an inner wall of the casing, and an end of the developing roller is sealed. When the end surface of the sealing member is located downwardly of a blade mounting surface at the time of assembly of the developing device, the back surface of the blade and the end surface of the sealing member are spaced apart. In this case, in which the developer may leak, the blade mounting surface is defined as a reference plane of the lower limit of the position of the end surface of the sealing member in the prior art.
In the developing device in the prior art, a sealing member having a C-shape in cross-section is fixed to the inner wall of the casing. An inclined surface which inclines upward with respect to a mounting surface for mounting the sealing member is formed on the inner wall of the casing. A ridgeline of the inclined surface is defined as a reference of the mounting position to mount the end surface of the sealing member.
However, in the developing device in the prior art, the reference plane of the end surface of the sealing member as the upper limit is not defined. Therefore, determining the proper position of the end surface of the sealing member upward with respect to the lower limit reference plane largely depends on the skill of an operator. When the developing device is assembled by an inexperienced operator, the end surface of the sealing member projects significantly upward from the blade mounting surface. In this case, since the sealing member is bent when being pressed by the blade, there is a problem that a gap is formed between the sealing member and the inner wall of the casing. In this manner, in the developing device in the prior art, positioning of the sealing member is liable to vary. Therefore, the assembling accuracy of the developing device is deteriorated, and hence assembly efficiency is low.